The present invention relates generally to wireless communication systems and, more particularly, to dynamically adjusting systems of a wireless communication system in response to changing network load and/or environmental conditions.
In typical cellular systems today, and more particularly, in code division multiple access (CDMA) systems, individual networks or cells are implemented with a fixed configuration. For example, across the network service area, cell sites are strategically placed to provide system access within each particular cell such that the aggregation of cells provides system access substantially throughout the network service area. Each such cell is typically substantially centered around a base transceiver station (BTS) antenna array and may be divided into multiple sectors in order to provide efficient spectrum use/reuse. Cell sectorization usually defines a fixed sector coverage size, i.e., the azimuth, the beam width, and the power for the antenna in each of those sectors is typically a fixed quantity over time.
For example, cells may initially be deployed throughout a service area which are each divided into an equal number of sectors, such as 3 non-overlapping sectors of 120xc2x0 as is common, each having a common orientation, such as orienting an xcex1 sector in a northerly direction, and a set power level associated therewith. This initial deployment is typically fixed and, therefore, does not change despite subscriber traffic and/or environmental conditions may change over time.
However, such a deployment may not adequately address network loading associated with subscriber positions, such as to accommodate areas of high loading associated with unusually dense subscriber populations such as highways, high rise office buildings, shopping malls, and even sports stadiums. Moreover, the loads within the network may not remain the same as when the network is deployed. For example, in the future, a new real estate development or highway may be constructed which will have the effect of shifting or increasing the cell traffic between one or more sectors and/or one or more cells. Similarly, network loading may present dynamics associated with subscriber behavior. For example, the above mentioned sports stadium may present heavy loading in a particular sector or sectors only during sporting events and otherwise present unusually low loading of the associated sector or sectors.
The above mentioned unbalanced loading of the network resources may lead to inefficiencies in the network and/or unacceptable or undesired operating characteristics. For example, sectorized cells often present trunking efficiency issues when a sector reaches capacity, i.e., a sector in which the subscriber is located may have reached capacity and therefore be unable to provide a traffic channel for desired communications, although traffic channels may be available in other sectors at the BTS. Additionally, sectors or cells operating at or near capacity may experience less than optimal signal quality while sectors or cells operating at lower loading may experience superior signal quality. Accordingly, sectorization efficiency is degraded when one sector reaches capacity (i.e., a sector in which the subscriber is located may have reached capacity, although capacity is available in other sectors of the BTS).
It would therefore be advantageous to have a system and method for monitoring network communication metrics, including metrics associated with communications as provided through a plurality of network resources, and thereby dynamically adjust operating parameters to redistribute network loading, or otherwise optimize network parameters.
The present invention is directed to a system and method which provides for the dynamic configuration/reconfiguration of network resources in a wireless communication system. Preferably, the present invention is implemented with respect to a cellular network, such as a network of code division multiple access (CDMA) cells, and operates to modify network operation based upon network measurements. For example, the present invention may operate to take performance measurements for each cell of a group of cells in a network and use those metrics to dynamically change the state of the network, or some portion thereof, as a function of these network measurements. Most preferably, the present invention measures or estimates the loading status of a network in order to drive changes to the network for load distribution.
According to a preferred embodiment of the invention, network measurements as utilized in modifying network operation are provided at least in part by communication control system statistics, such as switch statistics. The switch statistics so utilized may include performance pegs or performance counts, such as lost call rates, traffic usage, loading, call quality measures, and the like, that are accumulated in a system or systems, such as a switch of a mobile switching center (MSC), coupled to communication equipment associated with the cells, such as the cell site base transceiver stations (BTS). Accordingly, the system may control a group of cells, such as in the range of from approximately 10 to 200 depending on the number of cells that are coupled to a given mobile switching center, by determining performance measures for each sector of each cell in that group, and using those metrics to dynamically control one or more cell attributes and, thereby, change the state of the network.
Preferred embodiments of the present invention utilize empirical data, such as may be derived from drive testing within the network service area, in dynamically changing the state of the network. This empirical data may be utilized in conjunction with the aforementioned switch statistics to provide robust control decisions with respect to the network. For example, the aforementioned switch statistics may be analyzed to determine network resources, such as sectors or cells, experiencing excessive loading and/or undesired signal quality and those currently being under-utilized. Accordingly, a determination may be made as to network parameters to dynamically alter in order to drive the network to a more desired operation. In order to more predictably determine which particular network parameters should be altered to achieve the desired network operation, the aforementioned empirical data may be utilized in modeling the network propagation conditions, network resource coupling, and the like.
Preferably, a controller of the present invention analyzes network measurements to determine network parameter changes likely to bring about desired network operation and implements these parameter changes, or recommends these parameter changes to an implementing system, periodically. For example, a preferred embodiment controller analyzes switch statistics and estimates one or more network parameter configuration or parameter change to improve network operation and determines the network performance impact of the estimated parameter change using a modeling tool. Preferably, the modeling tool provides network signal propagation simulation, preferably using empirical data such as the aforementioned drive test data, to thereby predict the impact of an estimated parameter change. The network measurement analysis provided by the preferred embodiment controller optimizes both call quality and capacity in the network, although according to alternative embodiments the controller may optimize different parameters, such as to minimize the number of calls dropped at the expense of network capacity.
According to an embodiment of the present invention, the group of cells controlled include substantially conventional BTS technology, i.e., BTS systems which are not enhanced with xe2x80x9csmart antennaxe2x80x9d technology. Accordingly, the operation of the present invention may control power settings to alter cell or sector radiuses and thereby provide limited control over traffic loading among the cells and/or sectors. Moreover, preferred embodiments of the invention provide manipulation of other parameters, such as TT-drop, T-drop, T-add, neighbor lists, overload control thresholds, and the like. Accordingly, even without the aid of enhanced smart antenna technology, substantial control over traffic loading and signal qualities experienced among these cells and/or sectors may be effected.
Alternative embodiments of the present invention include one or more cells enhanced with smart antenna technology in the group of cells controlled. Accordingly, the operation of the present invention may adjust azimuths (sector orientations) and boundaries (sector widths and radii) of smart antenna enabled cell sites in addition to, or in the alternative to, adjusting parameters, such as power settings, TT-drop, T-drop, T-add, neighbor lists, and overload control thresholds, for the smart antenna enabled cell sites and/or the non-smart antenna enabled cell sites.
A technical advantage of the present invention is that operating parameter adjustments are made dynamically to optimize network performance, such as to optimize call quality and capacity in the network.
A further technical advantage is provided according to a preferred embodiment wherein network parameter adjustments are determined using switch metrics, as the dynamic adjustment of the network is based on the actual performance of the network and the network is optimized based upon criteria which is most important to the network.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.